The present invention relates generally to the manufacture of integrated circuit packages and, more particularly, to the manufacture and packaging of conductive clips for subsequent assembly into or onto a die or dies as used in integrated circuit packages, and, still more particularly, to elongated strips of conductive clips in which successive clips are transferred therefrom on a clip-by-clip basis via a transfer machine into or onto an integrated circuit package for assembly thereto or thereon.
In the manufacture of electronic components, including integrated circuits, the various sub-components (circuit dies, discrete components, conductive clips, etc.) are often supplied on or as part of an elongated strip that is often wound on a reel by the manufacturer with that reel then supplied to the customer. For example, integrated circuit dies are often supplied by the manufacturer as a paper strip or tape upon which the dies are adhered in a uniformly spaced apart relationship. The paper strip or tape is supplied to a pick-and-place machine which picks successive dies from the paper strip and places the so-picked dies on a leadframe or other substrate of an integrated circuit package. In addition to the paper strip or tape arrangement, other types of parts, including conductive clips, are formed on blank metallic strips by one or more die-cutting or die-stamping steps to form a succession of properly shaped and spaced-apart conductive clips on the metallic strip. As in the case of the paper tape scheme, the metallic strip can be wound upon a reel for delivery to the customer.
In general, the paper tape system arrangement is more expensive to manufacture and use, where conductive clips are involved, relative to arrangements in which a conductive clip is formed as a part of an elongated metallic strip.
FIGS. 1A and 1B illustrate a known conductive clip 10 of the type used, for example, in MOSFET power inverters; typically, these clips are used to make contact with the planar source or drain of a V-FET and effect an electrical connection to a conducive pad on a leadframe or other conductive part of a substrate. As shown, the conductive clip 10 includes a planar contact portion 12 and a riser or post 14 that is bent at some angle (e.g., about 90°) relative to the contact portion 12 of the conductive clip 10.
In a typical application, the planar contact portion is mounted atop a MOSFET to make electrical and mechanical contact with a source or drain thereof with the riser or post 14 extending to a contact pad on a leadframe or other substrate (not shown). The conductive clip 10 is typically fabricated from a conductive metal or alloy such as copper or a copper alloy.
As shown in FIG. 1C, the conductive clips 10 are often manufactured by subjecting an elongated strip of the metal starting-material to a succession of die-stamping steps that punch out material to form upper and lower rails 16 with appropriate sprocket holes 18 and to shape the conductive clips 10 with an additional metal-stamping step or steps to form the risers or posts 14. As shown, the conductive clips 10 are connected to the upper and lower rails by tiebars 20; while the example shown shows two tiebars 20, additional tiebars may be used.
FIGS. 1D and 1E are perspective views showing a conductive clip 10 and its tiebars 20. While not shown, each tiebar 20 can have a portion thereof that has a reduced cross-section or a reduced thickness or a score-line to allow the tiebars 20 to fracture or separate thereat when the conductive clip is pulled therefrom by a machine (not shown) for subsequent placement onto, e.g., a MOSFET chip of the type used in power inverters.
In general, the strips of so formed conductive clips 10 are wound on a reel (not shown) and supplied to the customer who often use a pick-and-place machine or robot to remove the conductive clips and place them into position in an integrated circuit undergoing assembly.